/*
 * Copyright (C) 2003, 2006, 2008, 2009, 2010, 2011 Apple Inc.
 * All rights reserved.
 * Copyright (C) 2008 Holger Hans Peter Freyther
 * Copyright (C) Research In Motion Limited 2011. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "flutter/sky/engine/platform/text/SurrogatePairAwareTextIterator.h"

#include <unicode/unorm.h>

using namespace WTF;
using namespace Unicode;

namespace blink {

SurrogatePairAwareTextIterator::SurrogatePairAwareTextIterator(
    const UChar* characters,
    int currentCharacter,
    int lastCharacter,
    int endCharacter)
    : m_characters(characters),
      m_currentCharacter(currentCharacter),
      m_lastCharacter(lastCharacter),
      m_endCharacter(endCharacter) {}

bool SurrogatePairAwareTextIterator::consumeSlowCase(UChar32& character,
                                                     unsigned& clusterLength) {
  if (character <= 0x30FE) {
    // Deal with Hiragana and Katakana voiced and semi-voiced syllables.
    // Normalize into composed form, and then look for glyph with base +
    // combined mark. Check above for character range to minimize performance
    // impact.
    if (UChar32 normalized = normalizeVoicingMarks()) {
      character = normalized;
      clusterLength = 2;
    }
    return true;
  }

  if (!U16_IS_SURROGATE(character))
    return true;

  // If we have a surrogate pair, make sure it starts with the high part.
  if (!U16_IS_SURROGATE_LEAD(character))
    return false;

  // Do we have a surrogate pair? If so, determine the full Unicode (32 bit)
  // code point before glyph lookup. Make sure we have another character and
  // it's a low surrogate.
  if (m_currentCharacter + 1 >= m_endCharacter)
    return false;

  UChar low = m_characters[1];
  if (!U16_IS_TRAIL(low))
    return false;

  character = U16_GET_SUPPLEMENTARY(character, low);
  clusterLength = 2;
  return true;
}

UChar32 SurrogatePairAwareTextIterator::normalizeVoicingMarks() {
  // According to
  // http://www.unicode.org/Public/UNIDATA/UCD.html#Canonical_Combining_Class_Values
  static const uint8_t hiraganaKatakanaVoicingMarksCombiningClass = 8;

  if (m_currentCharacter + 1 >= m_endCharacter)
    return 0;

  if (combiningClass(m_characters[1]) ==
      hiraganaKatakanaVoicingMarksCombiningClass) {
    // Normalize into composed form using 3.2 rules.
    UChar normalizedCharacters[2] = {0, 0};
    UErrorCode uStatus = U_ZERO_ERROR;
    int32_t resultLength =
        unorm_normalize(m_characters, 2, UNORM_NFC, UNORM_UNICODE_3_2,
                        &normalizedCharacters[0], 2, &uStatus);
    if (resultLength == 1 && !uStatus)
      return normalizedCharacters[0];
  }

  return 0;
}

}  // namespace blink
